ABSTRACT. This article shows how the substantive bias at the core of the present socio-economic constitution of the European Union is directly related to the characterization of economic freedoms (crucially, the right to freedom of establishment of corporations and the free movement of capital) as the key yardstick of European constitutionality. An empirically grounded reconstruction of the way in which the European Court of Justice applies the proportionality principle shows that the Luxembourg judges (1) assign the argumentative benefit to the holders of economic freedoms, (2) construct all other constitutional goods in the semblance of economic freedoms, and (3) use asymmetric proof standards when having to justify the adequacy and necessity of economic freedoms and other constitutional goods. As a result, under the cloth of projecting the way in which national constitutional courts review the constitutionality of legislation to the supranational level, the European Court of Justice has radically altered the substance of European constitutional law. In particular, the right to private property and entrepreneurial freedom (as operationalized through the four economic freedoms and the principle of undistorted competition) have been assigned an abstract and a concrete constitutional weight that places key public policies (social policies, tax policies, regulatory policies) off the realm of what is constitutionally possible. As a result, some of the collective goods at the core of the Democratic and Social Rechtsstaat have become extremely vulnerable. Focusing on the proportionality as practice by the European Court of Justice does not only provide us with insights into the nature and substance of European law, but also contributes to the general theoretical understanding of the principle of proportionality itself, in particular to a more detailed reconstruction of the relevant steps in proportionality review.